Pembrolizumab related perforated appendicitis

Pembrolizumab is a humanized monoclonal antibody IgG4 programmed cell death protein 1 antagonist, and its use in oncology has been increasing in recent years, providing durable and favorable responses and tolerable toxicity profiles in various types of cancer. We describe a case of pembrolizumab related perforated appendicitis in a patient with stage 3C malignant melanoma (MM).

A 70-year-old male patient who had no known disease was diagnosed with MM as a result of the excision of the mass on his right shoulder. The disease stage was stage 3C (pT4aN1bM0). Subsequently, adjuvant pembrolizumab treatment was started. A few days after the fourth maintenance course, he presented to the emergency department complaining of abdominal pain, nausea and vomiting. Emergency abdominal tomography showed a significant increase in the diameter of the appendix vermiformis, peritoneal thickening and appendiceal wall defects that could be significant in terms of perforation.

The mentioned finding and given the clinical presentation, was attributed to a perporating of the appendix, so the patient was hospitalized in the Department of Surgery and the patient underwent emergency appendectomy. Histological findings were consistent with appendicitis. After a day in the hospital, the abdominal pain subsided, C-reactive protein tended to decrease and the patient was discharged.

In patients who develop acute abdominal pain with or without diarrhea during immunotherapy, urgent imaging, endoscopic and clinical evaluation should be performed, and bowel perforation, although rare, should be considered as a potential complication of any immunotherapy.